fixed Base64 bug with last bytes processing

philanc · Nov 4, 2017 · 28835c2 · 28835c2
1 parent 373d36e
commit 28835c2
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Showing 2 changed files with 12 additions and 2 deletions.
diff --git a/plc/base64.lua b/plc/base64.lua
@@ -45,10 +45,12 @@ local function encode(s, filename_safe)
 		if lln > maxlln then st[#st+1] = "\n"; lln = 1 end
 	end
 	-- process remaining bytes and padding
+	local llx = #st  -- index of last st element with data
+	if st[llx] == "\n" then llx = llx - 1 end 
 	if rn == 2 then
-		st[#st] = string.gsub(st[#st], ".$", "=")
+		st[llx] = string.gsub(st[llx], ".$", "=")
 	elseif rn == 1 then
-		st[#st] = string.gsub(st[#st], "..$", "==")
+		st[llx] = string.gsub(st[llx], "..$", "==")
 	end
 	local b = concat(st)
 	if filename_safe then

diff --git a/test/test_base64.lua b/test/test_base64.lua
@@ -25,6 +25,14 @@ local function base64test()
 	assert(bd"YWF\nhY  W\t\r\nFhYQ" == "aaaaaaa")
 	assert(bd(be"\x00\x01\x02\x03\x00" ) == "\x00\x01\x02\x03\x00")
 
+	-- 171103 - add a test for the "n*54-1" bug 
+	-- (strings with n*54-1 or n*54-2 bytes)
+	for i = 0, 3 do
+		local ln = 3 * 54 - i
+		local s = ("a"):rep(ln)
+		assert(bd(be(s)) == s)
+	end
+
 end